Seven cochleas from 5 rats with spontaneous otitis media and 32 cochleas from 16 rats of similar age without otitis media, were examined by scanning electron microscopy to quantify cochlear hair cell loss. Loss of hair cell stereocilia was found in 3 cochleas with otitis media and was significantly increased when compared with uninvolved ears from animals of similar age. The hair cell loss associated with otitis media appeared to be most marked in the upper turns of the cochlea and increased in severity with the inflammation of the middle ear. The greater damage to hair at the basal turn suggests that this may be the result of influence of the middle ear inflammation on the cochlea through the cochlear window.